 
 (s/def ::parent ::node)
 
-(s/def ::children (s/coll-of ::node :kind set?))
+(s/def ::children (s/coll-of ::node :kind set? :into #{}))
 
 
 (defn create-node

(ns evermind.domain.core
  (:require [clojure.spec.alpha :as s]
            [clojure.spec.gen.alpha :as gen]))

(s/def ::node
  (s/keys :req-un []



(defn add-child
      ([parent child]
        (assoc parent :children
          (cljset/union (:children parent) #{child}))))

(s/fdef add-child
        :args (s/cat :parent ::node :child ::node)
